A printed page may include graphics, text and images. The graphics, text and images on a page are positioned at specific places on the page to provide a desired effect. A page description language (PDL) is generally used to provide instructions to a printer concerning how the graphics, text and images should be positioned on a page.
In most situations, an “interpreter” in the printer accepts the instructions provided by the PDL along with the necessary graphic, text and image objects. The interpreter generates appropriate raster image files to position of the ink dots which will form the desired printed page. PostScript™ which was developed by Adobe Systems Corporation is the most widely used PDL; however, there are many other PDLs that have been defined.
The page layout program PageMaker™ marketed by Adobe Systems Corporation is in widespread use to generate PostScript files. While the PageMaker program is in widespread use there are also are other somewhat similar programs such as those marketed under the trademarks “Quark Express” and “InDesign”.
A number of available interpreters take PostScript files and generate the raster images required by printers. One such interpreter is marketed by Adobe Systems. Another such interpreter is marketed under the trademark “PhonenixPage” by Xionics Document Technologies. Still another PostScript interpreter called “Ghostscript™” is freely available at various internet sites under the “Aladdin Ghostscript Free Public License”.
Programs that can insert digital watermarks into images are in widespread use. For example the widely used image editing program “Photoshop™” includes a mechanism for inserting a watermark into an image.